Vehicle signal control system

ABSTRACT

A vehicle control system includes, among other things, one or more functional warning units positioned in various positions in a vehicle. A central controller is configured to generate a desired state of the functional warning units and encode the desired state into a packet. Each of multiple remote controllers is functionally connected to at least one of the functional warning units. A functional connection between the central controller and the multiple remote controllers is configured to transmit the encoded packet from the central controller to each of the remote controllers. The remote controllers are configured to parse the desired state of each of the functional warning units in the encoded packet and set the state of each of the functional warning units based on the parsed encoded packet.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a continuation of U.S. application Ser. No.14/299,261, filed Jun. 9, 2014, now issued as U.S. Pat. No. 9,283,887,which claims the benefit of U.S. Provisional Patent Application No.61/832,494, filed Jun. 7, 2013, which are incorporated herein byreference in their entirety.

FIELD OF THE INVENTION

This invention relates generally to electrical control systems, and moreparticularly for controlling the visual and audible signaling systemslocated on vehicles.

BACKGROUND

One of the primary functions of a vehicle's signaling system is to drawthe attention of motorists and pedestrians to the vehicle. Accomplishingthis function provides safety to the driver of the vehicle andapproaching motorists and pedestrians. The installation and coordinationof the electronic visual and audible signaling devices is typically aresource-intensive process in terms of labor and materials. Eachsignaling module, such as needed for the control of a lightbar,perimeter lights, siren, headlight flashers, etc. must be hand-wired andthen programmed with configurations, flash patterns, and priorities.

Integrated wiring harnesses and control systems have been used forvehicle signaling. Some examples of these types of control systems aredisclosed in U.S. Pat. Nos. 5,422,623, 5,703,411, and 5,736,925functional warning units

Bader et al. U.S. Pat. No. 5,422,623 discloses an emergency signalingsystem for a vehicle that includes one or more signaling devices such asan emergency light located on a lightbar and a housing to enclose afirst control unit necessary for delivering power to the signalingdevice. A second control unit remote from the first is electricallycoupled to the electronics in the housing and stores and controls thesignal patterns for the signaling devices. The control units areconnected via a bus. Separate cabling from a battery carries power andreference ground wires to each of the control units.

Bella et al. U.S. Pat. No. 5,703,411 discloses a wiring harness andcontrol system for vehicle functional warning units directed at easy andquick installation into vehicles. A control unit, mounted on theunderside of the rear deck of the vehicle, couples to a user-controlledconsole. Branches of a wiring harness connected to the control unit arerouted to the lightbar, the headlights, warning lights and grille light.The control unit contains a load shedder circuit that distributes fusedpower to the lighting system elements.

Dawson et al. U.S. Pat. No. 5,736,925 discloses a modular lightingcontrol system for vehicle lighting control directed at a vehicle suchas an ambulance. A central processor processes commands from auser-controlled interface to route power to each of the signalingdevices under the control of the central processor. The signalingdevices are modular in that they may be selectively coupled to thecentral processor for a custom installation where the selective couplingrequires a wiring harness to connect each signaling device to thecentral processor.

SUMMARY OF THE INVENTION

An aspect of the invention relates to a method for controllingfunctional warning units on a vehicle containing multiple functionalwarning units that are controlled by a central controller and multipleremote controllers remote from the central controller that are connectedto the controller and to the functional warning units. The methodcomprises: generating an input relating to a desired state of thefunctional warning units in the central controller, encoding the desiredstate of the functional warning units into a packet in the centralcontroller; transmitting the encoded packet from the central controllerto each of the remote controllers across a network, wherein each remotecontroller is functionally connected to at least one of the functionalwarning units; parsing the desired state of each of the functionalwarning units in the encoded packet at each of the remote controllers,and setting the desired state of each of the functional warning units atthe remote controllers based on the parsed encoded packet. The centralcontroller is configured as a single master node and the one or moreremote controllers are configured as slave nodes on the network

In another aspect, the invention relates to a vehicle control system.The vehicle control system comprises one or more functional warningunits positioned in various positions in a vehicle, a central controllerconfigured to generate a desired state of the functional warning unitsand encode the desired state into a packet, multiple remote controllers,each of which is functionally connected to at least one of thefunctional warning units and a functional connection between the centralcontroller and the multiple remote controllers and configured totransmit the encoded packet from the central controller to each of theremote controllers wherein the functional connection is a network andthe central controller is configured as a single master node and themultiple remote controllers are configured as slave nodes on thenetwork. The remote controllers are configured to parse the desiredstate of each of the functional warning units in the encoded packet andset the state of each of the functional warning units based on theparsed encoded packet.

BRIEF DESCRIPTION OF THE DRAWINGS

In the drawings:

FIG. 1 is a top view of a vehicle with a modular, networked controlsystem according to an embodiment of the invention.

FIG. 2 is an isolated perspective view of the central controller of FIG.1.

FIG. 3 is a schematic view of the central controller of FIG. 2.

FIG. 4 is a flowchart showing communication between the centralcontroller and the remote controllers for setting the desired state ofvehicle functional warning units according to an embodiment of theinvention.

FIG. 5 is a flowchart showing a method the central controller may use togenerate the desired state of vehicle functional warning unitsfunctional warning units according to an embodiment of the invention.

DETAILED DESCRIPTION

Referring now to the drawings and to FIG. 1 in particular, a vehicle 12,such as an emergency vehicle, with a modular networked control system 10is shown. The vehicle 12, in addition to the standard elements of atypical vehicle, includes functional warning units to aid in specializedtasks required of the vehicle and its operators. For example, onespecialized task of an vehicle 12 is to provide active visual andaudible warnings to attract the attention of motorists and pedestriansas the vehicle 12 approaches. As shown in FIG. 1, to provide activevisual and audible warnings, the vehicle 12 may include a variety offunctional warning units such as a lightbar 26, a siren 28, a horn 30,directional lighting 34, spotlights 35, headlight flashers 38, dashlights 40 and perimeter lighting 42. Other active functional warningunits may be implemented depending upon the specific requirementsnecessary for the particular vehicle 12. Other active warning functionalunits may include public address systems, air horns, and load lights.While an “emergency vehicle” 12 is described, embodiments of thedisclosure can be applied to any vehicles 12, including, but not limitedto, land-based, sea-based, or air-based vehicles 12. Non-limitingexamples of additional vehicles 12 can include, for instance, cars,trucks, semi-trucks, cargo carriers, boats, aircraft, and trains.Furthermore, as used herein, a vehicle 12 does not need to include anindependent propulsion system, and can include, for example, train boxcars, barges, trailers, or semi-trailers.

All of the vehicle lights and other vehicle functional warning units maybe connected to the modular networked control system 10 and controlledin part by a user-interface on a control panel 32, preferably located ator near the console of the vehicle 12. Alternatively, the control panel32 may be implemented by a smart phone or tablet—either wired orwirelessly. Any device capable of providing a human-machine interface(HMI) may be used as the control panel 32 depending upon the particularimplementation of the invention. Other devices for providing HMI mayinclude a purpose-built touch panel device specifically for vehicles ora multi-button console control head.

To control and coordinate the active warning devices, a modularnetworked control system 10 further may be integrated into the vehicle12. A modular networked control system 10 may further include a centralcontroller 20 communicatively coupled to one or more remote controllers22 via a network connection. As shown in FIG. 1 the network connectionmay preferably be a Local Interconnect Network (LIN) 24. Other networksmay be implemented, for example, a Controller Area Network (CAN) or awireless local area network (WLAN).

The LIN 24 is a broadcast serial network connecting a single master nodewith one or more slave nodes. All messages on the LIN 24 are initiatedby the master node with a single slave node replying to a giventransmitted message. Communications across the LIN 24 may be carried ata 19.2 kbits/s data rate though other data rates may be implemented. Themaster and slave nodes are typically implemented as a microcontrollerbut may alternatively be implemented as application-specific integratedcircuits (ASICs).

Integrated into the central controller 20, the master node of the LIN 24initiates communications with the slave nodes that are integrated intoeach remote controller 22. The network topology, or organizationalhierarchy of the interconnected nodes on the LIN 24, may be any networkthat enables communications between the central controller 20 and theremote controllers 22. In one implementation, the network topology is astar network where all the slave nodes in the remote controllers 22 aredirectly connected to the master node in the central controller 20.However, other network topologies such as a tree topology may beimplemented to allow for remote controllers 22 to be daisy-chained suchthat some of the slave nodes of the remote controllers 22 arecommunicatively coupled to the central controller 20 through the slavenodes of other remote controllers 22.

The vehicle 12 functional warning units controlled by the modularnetworked control system 10 may be connected to the outputs of eitherthe central controller 20 or any of the remote controllers 22.Functional warning units such as the lightbar 26, siren 28 and horn 30may preferably be directly connected to the central controller 20whereas the directional light 34 or the headlight flashers 38 may bedirectly connected to one of the remote controllers 22. Theinteroperability provided by the modular networked control system 10enables vehicle 12 functional warning units to be connected to thecontroller deemed most accessible. This system enables short cablelengths to the controlled vehicle 12 functional warning units to boostdrive intensity, simplify and speed installation, and reduce harnessweight and cost.

The vehicle 12 functional warning units operably controlled by themodular networked control system 10 may not be limited to visual andaudible warning devices. For example, a gun rack 36 may be selectivelylocked and unlocked by a solenoid connected to either the centralcontroller 20 or a remote controller 22. Any 12-volt accessory socket 44or device may be operably controlled in the same manner; energized orde-energized according to an output of either the central controller 20or a remote controller 22.

Regardless of the particular network topology of the LIN 24, theconfiguration of the central controller 20 and the remote controllers 22on the LIN 24 asserts a modular design whereby additional remotecontrollers 22 may be plugged into the network without reconfigurationof previously installed elements of the networked system, particularlythe central controller 20. Installation of additional remote controllers22 requires a single power connection to be run from a power source tothe additional remote controller 22. Additional vehicle 12 functionalwarning units may connected to the additional remote controller 22without an additional wiring harness being run back to the centralcontroller 24. In one aspect of the invention, the ready addition of newremote controllers 22 and the ability to plug into the networked systemprovides for a highly scalable implementation.

Referring now to FIG. 2, the central controller 20 may now be described.The central controller 20 is an electrical device that includes a numberof electrical connections for providing energy to remotely connecteddevices including directly connected vehicle 12 functional warningunits. Additionally, the central controller 20 provides communication toremote controllers 22 coupled to the remote LIN communications port 110.A LIN status LED 112 may be provided for visual confirmation of thestatus of the network connection.

Power may be provided to the central controller 20 by power inputconnections further including, for example, a +12 Vdc connection 114 anda chassis ground connection 116. Preferably, the power input connectionsare further connected to a car battery, though other power sources maybe considered such as the alternator or a generator.

In addition to the LIN communications port 110, other communicationsports may be implemented. For example, a lightbar communications port118 may provide a direct communications channel between the lightbar 26and the central controller 20. Using this port, the lightbar 26 maydirectly communicate with the central controller 20. Likewise, a sirencommunications port 124 may be implemented. Both the lightbarcommunications port 118 and the siren communications port 124 may beprovided in tandem with status LEDs 119, 125 for visual confirmation ofthe status of the lightbar 26 and the siren 28.

The control panel 32 may be connected to the central controller 20 bythe control panel port 120. As previously described, the control panel32 may provide an HMI for connecting a user to the signaling system foroperation of the vehicle 12 functional warning units. A control panelstatus LED 121 may provide a visual indication as to the status of thecontrol panel 32.

A power status and/or fault LED 130 may be provided to visually indicatethe overall status of the central controller 20. Alternatively, thepower status and/or fault LED 130 may indicate a system fault. Forexample, the power status and/or fault LED 130 may flash according to apattern that indicates a diagnostic code in the event of a fault.

A plurality of switched power outputs 126 each with a status LED allowfor a number of additional direct connections between the centralcontroller 20 and vehicle 12 functional warning units. A microprocessorin the central controller 20 may selectively power any of the switchedpower outputs 126 according to the design of a particular signalingpattern or user-selected state by way of the control panel 32. Otherinputs to the system including those connected directly to the remotecontrollers 22 and user-initiated inputs may also determine in part thesignaling patterns. While any number of switched power outputs 126 maybe integrated into the central controller 20, in one preferredimplementation, the central controller 20 includes twenty switched poweroutputs.

A plurality of constant power outputs 130 each with a status LED allowfor a number of additional direct connections between the centralcontroller 20 and vehicle 12 functional warning units that need toalways have access to power. For example, a police cruiser may have aradio that is manually switched at the console of the vehicle. While anynumber of constant power outputs 130 may be integrated into the centralcontroller 20, in one preferred implementation, the central controller20 includes four constant power outputs.

Additional inputs to the central controller 20 beyond the control panelcommunications port 120 include an ignition input 132, an auxiliaryinput 134 and the current state of the emergency functional warningunits. These additional inputs provide alternative conditions such thatthe microcontroller may initiate signaling patterns either bycommunications across the LIN 24 or to directly connected switchedoutputs 126 in response to the current state of, for example, theignition switch or any of the emergency functional warning units.

Referring now to FIG. 3, the central controller 20 may preferablyinclude solid-state electronic components including a microprocessor 152for processing user inputs, connecting and managing the network andnetwork communications and coordinating the warning signals such asflashing patterns of the relevant 12 functional warning units. Couplingthe microprocessor 152 to both a power source 164 such as a 12 Vdcbattery, and the electrical load 168, a solid-state switching device 154may enable protective and diagnostic functions by provision ofovervoltage and undervoltage detection 156, over maximum currentdetection 158, open load detection 160 and programmable overcurrentdetection 162. The electrical load may further include both the inputsto the central controller 20 and the powered outputs such as the vehicle12 functional warning units controlled by the central controller 20 andmay be connected to chassis ground 170 as necessitated by the particularimplementation.

The overvoltage and undervoltage detection 156 may detect when thevoltage supplied to the central controller 20 is above or below thevoltage range at which the central controller 20 is designed to operatesuch as may occur during a power surge. The over maximum currentdetection 158 may similarly detect when the current exceeds a specificcurrent value such as may occur in a short circuit. The open loaddetection 160 may detect a no-load impedance indicative of an electricaldisconnect between the central controller 20 and the electrical load168.

The programmable overcurrent detection 162 may detect the presence ofexcess or larger than intended electric current along a conductor in thesolid-state switching device 154 often indicative of a short circuit oran excessive electrical load. In contrast to the over maximum currentdetection 158, the threshold used to determine whether the detectedcurrent level is excessive may be dynamic such that a programmablethreshold may be implemented and adjusted based in part upon theelectrical characteristics of the particular electrical load coupled tothe controller. The electrical load and it corresponding electricalcharacteristics may be characterized by the particular vehicle 12functional warning units connected to the central controller 20.

By integrating a solid-state switching device 154 into the centralcontroller 20 or a remote controller 22, the overall reliability of thecontrol system is improved without the need for electromechanicallyoperated relays or fuses. For example, the overcurrent detectionfeatures may eliminate the need for a fused circuit element, therebyeliminating the need for manual replacement of a fuse to restoreoperation of the modular networked control system in the event of asystem fault.

To communicate across the LIN 24, the central controller 20 may initiatecommunication with one or more of the remote controllers 22 according toa communications protocol that defines the format and syntax of thecommunicated data as well as the rules for data exchange between nodesof the network. According to the communications protocol of the presentinvention, the central controller 20 may initially transmit a datapacket. The data packet may be received by every remote controller 22 onthe LIN 24 and, according to an instruction embedded in the data packet,a specific remote controller 22 may reply with a second data packet tothe central controller 20. The combination of the initial data packettransmitted by the central controller 20 and the response packettransmitted by the indicated remote controller 22 may indicate a dataframe. The time required to complete a data frame dictates the refreshrate of the network communication. In a preferred embodiment of themodular networked control system 10, the refresh rate is approximately10 milliseconds (ms) though other refresh rates may be implementeddepending upon the design goals of a particular system.

Referring now to FIG. 4, the method of communicating the desired stateof the vehicle 12 functional warning units 200 from the centralcontroller 20 to the remote controllers 22 by the communication protocolaccording to the present invention will now be described. At the startof each data frame at step 210, the central controller 20 may generatethe desired state of the vehicle 12 functional warning units connectedto the central controller 20 by way of the LIN 24. The centralcontroller may then encode at step 220 the desired state of the vehicle12 functional warning units; that is, ON/OFF or powered/not powered,into the data payload of the packet as will be described below. Theencoding of the desired state may be a bitmapped representation whereeach vehicle 12 functional warning unit's state will be assigned a 0or 1. Then at step 230, the central controller 20 may transmit thepacket over the LIN 24 to the remote controllers 22. At step 240, eachof the remote controllers 22 may receive the packet and, generally,parse the packet and, more particularly, parse the bitmap representationof the desired state of the vehicle 12 functional warning units underthe control of the remote controller 22. A target remote controller 22may generate and send a response packet including an acknowledgement tothe central controller 20 over the LIN 24 at step 250. Then, at step260, the remote controllers 22 may set the current state of the vehicle12 functional warning units based on the desired state encoded in theparsed bitmap. At 270, the response packet may be sent from the targetremote controller 22 and received by the central controller 20designating the completion of the current data frame and the beginningof the next data frame where the process may be repeated.

Each data packet formed according to the communications protocol mayconsist of a first byte that encodes the length of the packet in bytes,a second byte that encodes the target of the packet and the type of dataencoded in the payload. The next sequence of bytes may encode thepayload or actual data encoded in the packet. The last two bytes of thepacket may encode a cyclic redundancy check (CRC). The CRC is awell-known error-detecting code used in digital networks to detectaccidental changes to raw data and need not be described in more detailhere.

Table 1 presents a tabular description of the structure of first byte ofthe communications protocol of the present invention. The first byte mayencode the length of the packet in bytes.

TABLE 1 Packet Length Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0Encodes the total number of bytes in the packet

Table 2 presents a tabular description of the structure of the secondbyte of the communications protocol of the present invention. The targetbit may be set to indicate the packet is being sent from the centralcontroller 20 to one of the remote controllers 22 or being sent from oneof the remote controllers 22 to the central controller 20. The moduleidentifier in the final three bits may encode which remote controller 22is transmitting or being targeted. The type or function of the dataencoded in the payload may be described by the three function bits ofthe packet header.

TABLE 2 Packet Header Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0Target Function Module Identifier

Table 3 presents a tabular description of the packet structure of thecommunications protocol of the present invention. As described above,the packet encodes the length of the packet in bytes, the target andfunction of the packet, the data payload for the encoded function in avariable number of bytes and the CRC for detecting errors in thetransmitted packet.

TABLE 3 Packet Length Packet Header Payload CRC 1 byte 1 byte Variablebytes 2 bytes

One encoded function indicates the data payload is the output enabledstate of every vehicle 12 functional warning unit connected to themodular networked signaling system. The data payload maps a single bitrepresentative of a desired ON/OFF state for each vehicle 12 functionalwarning unit. In this way, a single output packet encodes the desiredstate of every functional warning unit connected to the networkedsignaling system in a bitmap. For a network with five remote controllers24 where each remote controller 24 is coupled to ten functional warningunits, information for all 50 outputs is encoded in less than sevenbytes of data. Further, all of the remote controllers 24 may update thecurrent state of each functional warning unit based on that data.Therefore, all system outputs may update at approximately the refreshrate of the data frame of the communications protocol. With a preferredimplementation, the signaling system may update at approximately a rateof once every 10 ms. However, the refresh rate may ideally be selectedto achieve the fastest output update rate and lowest input latency.

As described above, the target remote controller 22 may send a responsepacket to the central controller 20 over the LIN 24 in the data frame.The response packet may act as an acknowledgment of the data packet sentby the central controller 20. The data payload of the response packetmay encode the current state of additional system inputs that aredirectly connected to the target remote controller 22. The state of theadditional inputs may be encoded as one of many possible states. Forexample, an analog voltage level of an additional input may be digitizedand encoded into the data payload of the response packet. In this way,the additional inputs connected to each remote controller 22 may bediscretized and subject to digital signal processing techniquesincluding, but not limited to, digital filtering. Other processingtechniques including the use of programmable thresholds may be used toprocess the encoded signals indicative of the state of the additionalinputs.

Additionally, the data payload of the response packet may encode faultsdetected on any of the functional warning units directly connected tothe target remote controller 22. Other ancillary data may be transmittedback to the central controller 20 in the data payload of the responsepacket. For example, the temperature of the remote controller 22 may besensed and then encoded into the data payload of the response packet.Any number of operational characteristics of the remote controllers 22,the functional warning units or even the vehicle 12 may be sensed andthen encoded into the data payload of the response packet.

By bitmap encoding the desired state of every vehicle 12 functionalwarning unit on the modular networked control system 10, the centralcontroller 20 may synchronize all of the devices, particularly thevisual and audible warning devices such as the lightbar 26, siren 28 andperimeter lighting 42 to establish any coordinated signaling patterndesired or required for the particular vehicle 12. In this way, flashpatterns for each lighting device may be encoded into the centralcontroller 20 and may be easily reconfigurable. New patterns may beuploaded into the central controller 20 to adapt to flashing patternrequirements that may differ across regions.

As previously discussed, at the start of each data frame at step 210,the central controller 20 may generate the desired state of thefunctional warning units connected to the central controller 20 by wayof the LIN 24. Referring now to FIG. 5, a method for generating thestate of functional warning units may now be described. The method maypreferably be implemented and executed by the microcontroller 152 in thecentral controller 20 though other controlling elements may beimplemented, for example, a software-based controller loaded into apersonal computer or mobile device connected to the central controller20. Initially, at step 310, the microcontroller 152 may clear the stateof conditional variables referred to as the “steady on” and “flashenable” variables. As described below, these variables may encodedesired behaviors of the functional warning units and may be set basedin part on the state of various inputs.

At step 320, the microcontroller 152 may set the current priority to aninitial level such as level one. Each input to the modular networkedcontrol system may be assigned a priority, for example, from one tothree and the input may have one of two input states; ON or OFF, and mayindicate one of three states for the output; ON, OFF or FLASH. Themicroprocessor 152 may then use the priority level of each input toorder the processing of the inputs to determine the output state of thefunctional warning unit. The microprocessor may evaluate the first inputat step 330 and may determine if the input's priority is the same as thecurrent priority at step 340. If the input's priority is the same as thecurrent priority then at step 350, the microprocessor 152 may determineif the output state should be turned OFF based upon the state of theinput. If the output state, as determined by the input state, is notOFF, then at step 360, the microprocessor 152 may determine if theoutput state should be set to FLASH based upon the input. If, based uponthe input state, the output is not FLASH, then at step 370, themicroprocessor 152 may determine if the output state should be turned ONbased upon the state of the input.

Based upon the decisions at steps 350, 360 and 370, the state of thesteady on and flash enable variables may be updated. If themicroprocessor, at step 350 determines that the output state should beturned OFF based upon the state of the input, then at step 352, thesteady on variable may be cleared and at step 354, the flash enablevariable may be cleared. If the microprocessor 152 determines that theoutput state should be set to FLASH based upon the state of the input,then, at step 362, the flash enable variable may be set to the currentpriority level, that is the priority level of the input. If themicroprocessor 152 determines that the output state should be turned ONbased upon the state of the input, then, at step 372, the steady onvariable may be set to the current priority level that is the prioritylevel of the input.

If, at step 340, the input's priority is not the same as the currentpriority or after evaluating the input's state and updating the relevantvariables at any of steps 354, 362, 372 and 370, the microprocessor 152may determine if all inputs to the control system have been evaluated.If not, then at step 381, the microprocessor 152 may evaluate the nextinput and proceed to the evaluating steps starting with determining ifthe input's priority is the same as the current priority at step 340.Upon evaluation of all the inputs, the microprocessor 152 may incrementthe current priority at step 382. The microprocessor, at step 384 maythen determine if the current priority level exceeds the highestpriority level of the system, for example a priority level greater thanthree. If the microprocessor determines at step 384 that the currentpriority level is less than or equal to the maximum priority level forthe system, the evaluation of the inputs starting with evaluation of thefirst input at step 330 may be repeated for the current priority level.

When the microprocessor 152 determines at step 384 that the currentpriority level exceeds the highest priority level of the system, themicroprocessor 152 may evaluate the flash enable variable at step 386.If the flash enable variable is greater than zero, the microprocessor152, at step 388, may set the output state of the functional warningunit to flash per the flash pattern associated with the priority levelencoded in the flash enable variable. If, at step 386, the flash enablevariable is zero or after the output state of the functional warningunit is set to flash at step 388, the microprocessor 152, at step 390,may determine if the steady on variable is greater than zero. If thesteady on variable is greater than zero, then at step 392, themicroprocessor 152, may compare the values of the steady on and flashenable variables. If the steady on variable has the same or a highervalue than the flash enable variable, then at step 394, the output stateof the functional warning unit may be set to ON.

As described, the microprocessor 152 may determine the output state ofthe functional warning units based in part on the activated input withthe highest priority. Table 4 presents an example set of inputs withtheir output state and priority level. Table 5 present four examplescenarios to demonstrate the relationship between the output state andthe priority of the inputs. Scenario 1 results in a FLASH output statebecause input three is ON and when input three is ON and has the highestpriority of the inputs in the ON state, it directs an output state to beset to FLASH. Scenario 2 results in a FLASH output state because inputsix with a priority level of three is ON and set to FLASH. Scenario 3results in an OFF output state because input five with a priority leveltwo is ON and directs an output of an OFF state. Scenario 4 results in aFLASH output state because input three with a priority level two is ONand set direct an output to a FLASH output state.

TABLE 4 Input Number 1 2 3 4 5 6 7 8 9 Output ON OFF FLASH ON OFF FLASHON OFF FLASH state Priority 1 1 2 2 2 3 3 1 1 Level

TABLE 5 Input Number 1 2 3 4 5 6 7 8 9 Scenario 1—Resulting Output FLASHInput ON ON ON OFF OFF OFF OFF OFF OFF State Scenario 2—Resulting OutputFLASH Input ON ON ON ON ON ON OFF ON ON State Scenario 3—ResultingOutput OFF Input ON ON OFF OFF ON OFF OFF OFF OFF State Scenario4—Resulting Output FLASH Input ON OFF ON OFF OFF OFF OFF ON OFF State

If the value of the steady on variable at step 390 is greater than zeroand also greater than the flash enable variable then the output isencoded to ON at step 394. The microprocessor 152 may then encode theoutput state at step 396 for the data payload of the packet to be sentby the central processor 20 in step 220 of the communication protocoldescribed in FIG. 4. As previously described, the encoding scheme foroutput states encoded in the data payload of the packet to be sent viathe LIN 24 to the remote controllers 22 allows for bitmapped encoding ofON/OFF states. When an output state at step 396 is set to FLASH, themicroprocessor 152 may further encode the output state by an additionalprocess that encodes the flash pattern for the output based on thepriority level of the relevant input. The microprocessor at step 392 maydetermine if a particular FLASH output state should be encoded into thedata payload of a packet as ON or OFF based on a timed sequence of stepsthat determine the flash pattern. In this way, the flash pattern is aseries of instructions in the microprocessor that may encode a flashpattern as a predetermined sequence of ON and OFF states as a sequenceoutput. For example, a FLASH output may result in one set of functionalwarning units being cycled from ON to OFF every 5 data frames while asecond set of the vehicle's 12 functional warning units are cycled fromON to OFF for 5 data frames and then from OFF to ON for 2 data frames.Consequently, the temporal resolution for the generated flash patternsis synchronized with the data frame rate, for example 10 ms. Therefore,the central controller 20 may simply send an ON or OFF value to theremote controller 22 for each output functional warning unit when inFLASH mode.

The central controller 20 may have multiple flash patterns programmedinto the microprocessor 152. The method to generate the output statesmay be applied to determine the output state of each functional warningunit individually or en masse depending upon the desired implementation.Additionally, the method may be triggered by one of many conditions,including the detection of a changed state of an input. Other triggersmay include those based on timers or other external sensors. The systemand method described above may include the capacity to handle complexinput matrix triggers. For example, the system may handle multipleinputs by processing Boolean logic statements assembled based upon thestate of the system and the set of inputs to the system.

While the invention has been specifically described in connection withcertain specific embodiments thereof, it is to be understood that thisis by way of illustration and not of limitation. Reasonable variationand modification are possible within the scope of the forgoingdisclosure and drawings without departing from the spirit of theinvention which is defined in the appended claims.

What is claimed is:
 1. A method for controlling functional warning unitson a vehicle containing multiple functional warning units that arecontrolled by a central controller and multiple remote controllersremote from the central controller that are connected to the controllerand to the functional warning units, the method comprising: generatingan input relating to a desired state of the functional warning units inthe central controller; encoding the desired state of the functionalwarning units into a packet in the central controller; transmitting theencoded packet from the central controller to each of the remotecontrollers across a network wherein each remote controller isfunctionally connected to at least one of the functional warning units;parsing the desired state of each of the functional warning units in theencoded packet at each of the remote controllers; and setting thedesired state of each of the functional warning units at the remotecontrollers based on the parsed encoded packet; wherein the centralcontroller is configured as a single master node and the one or moreremote controllers are configured as slave nodes on the network andwherein the step of encoding the desired state into a packet includesembedding into the packet a data payload that contains a bitmap of thedesired state of the functional warning units.
 2. A method forcontrolling functional warning units on a vehicle containing multiplefunctional warning units that are controlled by a central controller andmultiple remote controllers remote from the central controller that areconnected to the controller and to the functional warning units, themethod comprising: generating an input relating to a desired state ofthe functional warning units in the central controller; encoding thedesired state of the functional warning units into a packet in thecentral controller; transmitting the encoded packet from the centralcontroller to each of the remote controllers across a network whereineach remote controller is functionally connected to at least one of thefunctional warning units; parsing the desired state of each of thefunctional warning units in the encoded packet at each of the remotecontrollers; and setting the desired state of each of the functionalwarning units at the remote controllers based on the parsed encodedpacket; wherein the central controller is configured as a single masternode and the one or more remote controllers are configured as slavenodes on the network and wherein encoding the desired state of thefunctional warning units into a packet includes encoding a flash patternfor one or more functional warning units as a predetermined sequence ofON and OFF states in consecutive packets.
 3. The method of claim 2wherein the act of generating the state of the functional warning unitsincludes providing an input from a user to the central controller. 4.The method of claim 2 wherein the act of generating the desired state ofthe functional warning units includes providing multiple inputs to thecentral controller.
 5. The method of claim 4 wherein the act ofgenerating the desired state of the functional warning units includesprioritizing the one or more inputs.
 6. The method of claim 4 where atleast one of the multiple inputs includes an input from a secondvehicle.
 7. The method of claim 2 wherein the transmitting act isrepeated at a predetermined frame rate.
 8. The method of claim 2 whereinthe transmitting act takes place over a local interconnect network(LIN).
 9. The method of claim 2 wherein the transmitting act takes placeover a wireless network.
 10. An vehicle control system comprising: oneor more functional warning units positioned in various positions in anvehicle; a central controller configured to generate a desired state ofthe functional warning units and encode the desired state into a packetand encode a flash pattern for the one or more functional warning unitsas a predetermined sequence of ON and OFF states in consecutive packets;multiple remote controllers, each of which is functionally connected toat least one of the functional warning units; and a functionalconnection between the central controller and the multiple remotecontrollers and configured to transmit the encoded packet from thecentral controller to each of the remote controllers wherein thefunctional connection is a network and the central controller isconfigured as a single master node and the multiple remote controllersare configured as slave nodes on the network; wherein the remotecontrollers are configured to parse the desired state of each of thefunctional warning units in the encoded packet and set the state of eachof the functional warning units based on the parsed encoded packet. 11.The system of claim 10 wherein the functional warning units include oneor more lightbars, headlights, taillights, alley lights, gun locks,horns, perimeter lighting, or sirens.
 12. The system of claim 10 whereinthe connection is a local interconnect network (LIN).
 13. The system ofclaim 10 wherein the connection includes a single network bus.
 14. Thesystem of claim 10 wherein the central controller is further configuredto be responsive to one or more inputs to set the current state of thefunctional warning units.
 15. The system of claim 14 where the inputsinclude a human-machine interface (HMI) and the current state of theignition switch.
 16. The system of claim 14 where the inputs include thecurrent state of at least one of the functional warning units.
 17. Thesystem of claim 14 wherein the central controller is further configuredto prioritize the one or more inputs.
 18. The system of claim 10 whereinthe central controller includes a solid-state switching deviceconfigured to detect one or more of an over voltage condition, an overcurrent condition, an open load condition, and an over temperaturecondition.